Abstract:Sunflower crops (Helianthus annuus L.) are a source of pathogens that can be transmitted by means of the seeds. An alternative for the treatment of seeds can be the application of an ozone compound, which has been used in various segments to eliminate microorganisms. Three lots of the Embrapa 122 variety have been used to assess the efficacy of ozone to control pathogens in sunflowers seeds. To typify the profile of the lots we have determined the moisture content, the first germination counting, the germination, the germination speed index, emergence, initial stand, emergence speed index and health. The lots have been stored in an ozone-rich environment for periods of 20, 60 and 120 minutes and without ozone (control). After the treatments, the seeds were tested to assess their health and physiological quality through the said tests as well as a test for accelerating aging, tetrazolium and incidence and severity of fungi. It has been concluded that the treatment for H. annuus seeds, Embrapa 122 variety, with ozone concentration of 1741 ppmv (0.24 g/h), for 60 minutes, reduces the fungal presence of Alternaria sp., Fusarium sp., Aspergillus sp. and Penicillium sp. without affecting their physiological potential.

Na busca de sementes e plantas de alto padrão de qualidade, a utilização do silício pode ser interessante na agricultura, pois pode incrementar a produtividade, regular a perda de água, melhorar a taxa fotossintética,aumentar a rigidez da estrutura dos tecidos entre outros. Dessa forma, objetivou-se com essa pesquisa verificar o efeito da aplicação foliar de silício no crescimento, fisiologia de plantas de trigo e na qualidade de sementes de trigo produzidas. Empregou-se o delineamento experimental em blocos casualizados com fatorial 2x4 com 5 repetições, onde os tratamentos foram compostos por duas cultivares de trigo (BR18 e BRS254) e quatro dosagens da formulação comercial Supa Sílica da marca Agrichem®: 0,0 L ha-1, 0,5 L ha-1, 1 L ha-1 e 2,0 Lha-1, divididas em três aplicações nos estádios de perfilhamento, emborrachamento e floração. Foram feitas avaliações fisiológicas e filotécnicas como fluorescência da clorofila, taxa de transporte de elétrons, diâmetro, altura, massa seca, número de perfilhos e fitoxidade. A qualidade fisiológica das sementes foi avaliada pelosseguintes testes: germinação, primeira contagem, índice de velocidade de germinação, emergência, estande inicial. A cultivar BR18 produziu maior quantidade de perfilhos, massa seca, clorofilas A, B e total e de Fv/Fm do que a cultivar BR254 com aplicação foliar de silício. A taxa de transporte de elétrons, fluorescência inicial e a fitotoxicidade forma influenciadas negativamente pelo aumento das doses de silício foliar para ambas as cultivares. A aplicação de silício foliar não interfere na qualidade das sementes de trigo, porém melhorou o desempenho de emergência, estande inicial e IVE da cultivar BR18.

No abstract

Kale (Brassica oleracea var. acephala) has great importance due to its easy propagation, acceptability and nutraceutical properties. The aim of the present work was to make methodological adjustments to conduct the tetrazolium test in kale seeds. Pre-tests were initially carried out to assess the priming time at 20 °C for 10 and 14 hours (times defined by the imbibition curve) and methods of removing the coat of kale seeds (total removal of the seed coat; cut in the distal region to the embryonic axis; longitudinal cut along the longest axis and whole seeds). Subsequently, the most efficient methodologies were evaluated using different concentrations of the tetrazolium salt solution (0.075%; 0.2%; 0.5% and 1.0%) and times (2, 4 and 6 h) of seed immersion in the solution, using four lots. The seeds were analyzed individually and classified as viable or non-viable. The tetrazolium test is efficient for evaluating the viability of kale seeds, providing results correlated with germination. Kale seeds should be primed between paper for 10 hours at 20 °C, and the seed coat should be removed for immersion in a 0.5% tetrazolium salt solution for 4 hours at 30 °C.

For the germination of sweet potato (Ipomoea batatas) seeds to occur, it is necessary to overcome dormancy, which makes it difficult to assess their physiological potential. The aim of this research was to define a methodology to overcome the dormancy of sweet potato seeds and use image analysis to determine their physical and physiological quality. Four genotypes of sweet potato seeds were used, namely UFVJM-5, UFVJM-22, UFVJM-38 and UFVJM-65. To overcome dormancy, chemical scarification with 98% H2SO4 for 10 and 20 minutes, hot water at 95 °C for 10 and 20 minutes, and mechanical scarification with electric grinder were tested. To evaluate the physical quality, the seeds were analyzed with X-rays and classified as intact, empty and malformed seeds. Using the GroundEye® system, the characteristics of color dominance, seed geometry and seedling length were quantified. Treatments with mechanical scarification with grinder and 98% sulfuric acid, for an immersion period of 20 minutes, are efficient to break dormancy in sweet potato seeds. There are genetic divergences between sweet potato genotypes, promoting the formation of different groups. The characteristics of color and geometry of the seeds are the ones that most contribute to genetic diversity of genotypes.